Syringe pump



SYRINGE PUMP Sheet Filed June 2, 1967 June 3, 1969 0. ROSENBERG3,447,479

SYRINGE PUMP Filed June 2, 1967 Sheet 3 of 2 :ez: gm-gm flaw UnitedStates Patent York Filed June 2, 1967, Ser. No. 643,083 Int. Cl. A61m1/00; F04b 1/04, 21/02 US. Cl. 103-153 12 Claims ABSTRACT OF THEDISCLOSURE A syringe pump is provided in which the syringe is easilydetachable from the assembly and replaceable with a syringe of the sameor of a different size.

The syringe pump has a drive mechanism, a coupling means to hold theplunger of the syringe and the drive means in operative engagement,engaging the end of the plunger in an easily detachable manner, andadapted to accommodate syringe plungers of different sizes, and amounting means holding the syringe body in a fixed position relative tothe drive means, engaging the syringe body in an easily detachablemanner, and adapted to acc0m modate syringe bodies of different sizes.

This invention relates to a syringe pump, and more particularly, itrelates to a syringe pump in which the syringe is readily detachable andreplaceable.

Surgical syringes are readily available and can accurately meter fluid.Moreover, since they employ a piston and cylinder, they have provedsuitable for accurately pumping measured small amounts of fluid forlaboratory use.

One such laboratory syringe pump is shown by Wiley et al. in US. PatentNo. 3,259,077. Wiley et al. disclosed a pump assembly which employs asurgical syringe at the means for pumping measured amounts of fluid.However, the valve assembly that is associated with the system is rathercomplicated and the pump itself relatively expensive to manufacture.Moreover, the syringe is not readily detachable from the assembly andthe assembly is not adapted to readily employ a syringe of another size.

In a laboratory, it is often necessary to have several pumps ofdifferent sizes for different pumping operations. However, most oftenonly one pump is in use at a time. It is therefore advantageous toprovide a syringe pump which can employ syringes o'f diflerent sizes andin which the syringe can be readily detached and replaced with anotherfor quick conversion. The instant assembly provides such a syringe pumpassembly. Moreover, this syringe pump needs only one drive mechanism,one valve assembly, and several syringes to provide a versatile pumpwhich can perform the functions of several pumps at lower cost.

The instant pump comprises a base; a fluid line; a syringe having a bodyportion, a pumping plunger reciprocably movable between limits in thebody portion, and an aperture in the body portion communicating with thefluid line for receiving fluid from and discharging fluid to the fluidline upon reciprocation of the plunger; means holding the syringe on thebase in an easily-detachable manner, and adapted to accommodate syringesof diflerent sizes; a check valve assembly in the fluid linecommunicating with the syringe such that fluid can proceed through thefluid line in only one direction, whereby fluid is pumped through thefluid line upon reciprocation of the plunger; and drive meansoperatively connected to the plunger for reciprocably moving the plungerwithin the syringe body to pump the fluid in the fluid line.

The syringe used in this syringe pump assembly is preferably an ordinarysurgical syringe. Such syringes comprise a hollow sylinder having anapertured tip formed at one end and a laterally extending flange at theother end. The flange is normally provided as a convenient place forgripping the syringe when it is held in one hand. A plunger is providedfor reciprocable movement within the cylindrical body. The plunger hasan end which extends from the flanged end of the syringe. The plunger isfitted in a substantially fluid-tight seal against the walls of thecylindrical body of the syringe and forms with the body a piston andcylindrical pump. The seal on the plunger is normally maintained by an Oring or the like. On the pressure stroke the plunger pump forces fluidfrom the syringe body through the tip, and on the vacuum stroke theplunger draws fluid into the body through the tip, for the next pumpingor pressure stroke.

Surgical syringes are normally made from plastic material such aspolyethylene or polypropylene; however, syringes made of any materialthat is inert to the fluid being pumped, such as glass, nylon, andTeflon, are suitable for use in this invention. The material ispreferably transparent or translucent, but it need not be.

The syringe can be of generally any size, length and diameter, and ofany capacity. Capacities from about one cc to about ten cc are preferredfor use in pumps of this invention.

The syringe is supported on a base which can normally also serve tohouse or support the drive means for the assembly. The case can be madefrom any material, such as wood, plastic, or metal. Plastic materials,such as nylon and polycarbonates, are preferred. The base can be formedin any desired or convenient shape, such as a cube.

The base can hold or otherwise support one or more syringes. If aplurality of syringes are used, they can be positioned in any location,or grouped in any manner on the base. It is to be noted, however, thatif a plurality of syringes are provided they can all be driven by thesame drive mechanism by proper positioning of the syringes on the base.This can be accomplished by arranging the syringes with their plungersall adjacent to the drive mechanism. One way of doing this is to arrangethem in a star-like configuration about the drive member.

If only one syringe is supported on the base, it normally will bepositioned tip-end up, in a generally vertical position. The syringeshould be supported on the base by mounting members that permit easydetachment of the syringe from the base. The mounting members shouldalso be adjustable to accommodate syringes of different sizes.

One preferred mounting member is a clamp of the snap clip type. The snapclips can be provided on the base in position to grasp the flangedportion of the syringe and, additionally, if desired, the cylindricalbody of the syringe also.

The snap clips which engage the flanged portion of the syringe preventany longitudinal displacement of the syringe which might occur when theplunger is reciprocated. Moreover, by providing clips which grap theflanged portion guide firmly, it is possible to prevent any motion ofthe syringe at all. This makes it possible to employ only one set ofclips which engage the flanged portion of the syringe to secure thesyringe in position on the base.

If desired, an additional snap clip can be provided to engage andsupport the cylindrical body against any lateral displacement of thesyringe which might other- Wise occur.

Snap clips are preferred, since they are readily available and easilyfabricated for special application. Moreover, they are long wearing andsimple to use. They permit easy removal and replacement of the syringeon the assembly and can readily accommodate a wide range of syringes ofdifferent sizes without any special adjustment.

A preferred snap clip for the flanged portion of the syringe comprises apincer-shaped clip employing a rigid support member and a resilientpincer arm which bears against the support. The flange is insertedbetween the pincer arm and the support and is held in position therebetween by the spring force of the arm. This type of clip is preferred,since it has been found to provide firm support for the syringe on thebase without any additional support members. It is adapted to readilyaccommodate syringes of different sizes since the size of the flangedportion of the syringe does not vary greatly for different syringes. Aclip of the type described above also permits easy removal of a syringefrom the assembly.

Snap clips are normally made at least in part of a highly resilientmaterial, such as spring steel, or hard long-wearing resilient plastics,such as nylon or polypropylene.

Other suitable snap clips can be preferably C- or U- shaped, dependingupon the portion of the syringe they are to hold. For example, a snapclip that is positioned to hold the cylindrical body should be C shapedand be oriented such that the body of the syringe is inserted into theopen mouth of the C.

Another snap clip which can be used to engage the flanged portion of theplunger should be normally shaped as a narrow U and be oriented suchthat the flange is inserted into the narrow open slot between the armsof the U.

It is also possible to provide snap clips which are of adjustabletension to ensure a tight grip on any size syringe used. Other mountingmembers for holding the syringe in place, such as clamps of all typescan be used. It is to be noted, however, that any mounting membersprovided should be readily adjustable and should be adapted to hold thesyringe in a manner such that removal of the syringe from the assemblyis readily accomplished.

The mounting members can be fixed in position on the base, and need notbe movably mounted in order to hold different capacity syringes. This isdue to the fact that the bodies of syringes of different capacitiesnormally vary most in body diameter. This, however, does not affect thepositioning of the mounting members, and thus they need not be movableon the base. However, if desired, the mounting members can be madeadjustable on the base to occupy the same relative position for eachdiffer ent syringe.

The tip of the syringe communicates with a check valve assembly throughwhich the fluid is pumped. The check valve of the instant invention cancomprise a check valve chamber having an inlet and an outlet, checkvalves at the inlet and the outlet, and an aperture adapted to receivethe tip of the syringe. The check valves ensure that fluid can flow onlyin one direction as the plunger reciprocates. Duckbill valves arepreferred as the check valves. However, poppet valves, flap valves, orthe like can also be used.

The aperture in the chamber should be provided with means to ensure afluid tight fit about the tip of the syringe. However, it should also beadapted for the easy removal of the syringe therefrom, since the syringeis normally removed from the check valve assembly when it is dismountedfrom the base. The fit should also be such that it accommodatesdifferent syringes. It is to be noted, however, that the tip ofdifferent syringes is a generally frustoconical member which is the samesize, regardless of the syringe body size. Therefore, normally the fitneed not be one that is adjustable.

It is preferred that the fit is accomplished by merely forming theaperture of the chamber as a frustoconical passage which matches thetaper of the frustooonical tip of the syringe. When the tip of thesyringe is placed into this passage, the exterior of the tip engages andforms a seal against the walls of the passage due to the close fit. Thisprovides a tight seal which can withstand high fluid pressure withoutleaking. However, to remove the syringe, it is merely necessary to twistthe syringe and 4 thereby break the seal. The syringe can then be easilyremoved from the check valve chamber.

The fit of the syringe tip in the check valve chamber can also beaccomplished by providing .a resilient sealing ring at the aperture ofthe check valve assembly through which the tip is inserted. A sealingring can grip the tip of the syringe and maintain a fluid tight sealthereagainst when the tip is in position but also permits easy removalof the syringe. :It is also possible to make the entire check valveassembly housing of resilient material, such as rubber and thus avoidthe necessity of providing a separate sealing ring to seal against thesyringe tip.

Another method of fitting the syringe to the check valve chamber is byproviding a threaded engagement or bayonet coupling of the syringe andcheck valve assembly. It is necessary however in these embodiments tospecially modify the syringe tip for the coupling. Therefore, thesemeans for coupling are less preferable than those described above.

The check valve assembly can, if desired, be permanently affixed to thesyringe as a part thereof. Since it is a simple and inexpensivemechanism, it can be replaced when the syringe is replaced. Thiseliminates the necessity of cleaning the check valve assembly to removeresidual fluid after each fluid is pumped through it.

The check valve assembly need not be supported on the base, since it ismounted on the syringe tip and supported thereby. However, it desired,snap clips or other similar mounting members can be provided on the baseto hold the check valve assembly in position. The mounting members, insuch a case, can be adjustably positioned on the housing so that theycan support the check valve assembly regardless of the length of thesyringe.

The drive mechanism that is used in the instant pump assembly toreciprocate the plunger of the syringe is prefenably an eccentric drivemeans that is powered by an electric motor. The motor can be housed inthe base and be operatively connected to the eccentric drive member by amotor shaft. The eccentric drive member can be a cam, a Scotch yokeassembly, or the like. The drive mechanism, however, need not be aneccentric drive apparatus. Any mechanism adapted to convert therotational motion of the motor to translational movement of the plungerof the syringe is suitable.

The drive mechanism should be disposed in a position such that rotationof the motor causes the drive mechanism to bear against the plunger ofthe syringe and cause reciprocal movement thereof.

If a cam drive is used, a spring can be employed as part of the drivemechanism to return the plunger to its original position, after the camhas formed the plunger to move inwardly. A comperssion spring disposedbetween the flanged portion of the cylindrical body and the end of theplunger is preferred.

If a Scotch yoke is used, no additional means need be provided towithdraw the plunger from the cylinder since the yoke both forces theplunger inwardly and withdraws it from the cylindrical body. It is to benoted that both of the above drive mechanisms can be adapted to actuatea plurality of syringes mounted at a plurality of different positions onthe base.

The extent of the movement of the plunger determines the amount of fluidpumped on any one stroke. Means, such as stops, set screws, and lostmotion linkages can be provided to precisely control the extent of theplunger movement.

In operation, the rotation of the motor shaft rotates the drivemechanism to cause reciprocal motion of the plunger in the syringe body.When the plunger moves inwardly into the body, fluid in the syringe bodyand in the check valve chamber is pumped from the outlet thereof. As theplunger is withdrawn from the body, fluid is drawn from the inlet intothe check valve assembly and into the syringe body for transfer from theoutlet of the assembly on the next stroke.

The syringe can be readily detached from the assembly by merelywithdrawing it from the snap clips and removing the check valve chamberfrom the syringe tip. A syringe of a different size can be easilysubstituted in the assembly merely by inserting it into the snap clips,and placing the check valve chamber on the tip.

The instant assembly is simple, versatile, and convenient to use. It canbe fabricated quite inexpensively since nearly every portion of theassembly with the exception of portions of the motor can be made ofinexpensive materials, such as plastic. Thus, this invention provideswith a minimal expense a pump which can perform the functions of severalpumps.

Preferred embodiments of this invention will now be described inconnection with the following drawings, in which:

FIGURE 1 is a plan view of a syringe pump of this invention with thecheck valve assembly shown in crosssection;

FIGURE 2 is a plan view of a syringe pump in accordance with thisinvention employing a plurality of syringes.

FIGURE 3 is a plain view of another embodiment of a syringe of thisinvention with the check valve assembly shown in cross-section.

In FIGURE 1, a syringe pump in accordance with this invention is shown.It comprises a base 1, housing a mo tor '(not shown). The motor isoperatively connected to Scotch yoke assembly 2 by a drive wheel 5mounted to a motor shaft (not shown). The Scotch yoke assembly iscomposed of a rectangular bar 3 rotatably mounted on a pin 4. The pin 4is eccentrically mounted relative to the drive wheel 5. A C-shaped clamp6 surrounds rectangular bar 3 and operatively engages an end 7 of aplunger 8 of a syringe 10. The C-shaped clamp 6, the drive wheel 5 andthe rectangular bar 3 are all formed of plastic.

The syringe 10 has a tip portion 12 and a cylindrical body portion 11which terminates in a flange 9 at the end thereof. The plunger 8 ismounted for reciprocal movement within the cylindrical body 11. Theplunger 8 has a piston 13 thereon, having an O-ring sealing member 14thereabout to ensure a leak-proof seal between the piston 13 and thecylindrical body 11 of the syringe.

The syringe 10 is vertically positioned tip end up, and is supported onthe base by snap clips 15 which engage the flange 9, and a snap clip 17which engages the cylindrical body. These snap clips are made of springsteel and are quite resilient. The syringe 10 can be readily removedfrom their grasp and replaced with a syringe of the same or of adifferent size. The clips can accommodate syringes of one cc. to aboutten cc. capacities. The check valve assembly 19 is located on thesyringe tip 12 and communicates therewith. It is supported on the baseby snap clips 26. The check valve assembly comprises a check valvechamber 20 having an inlet 21, and an outlet 22. Duckbill valves 24a and2412 are provided at the inlet to ensure fluid flow only from the inletto the outlet in one direction. The tip of the syringe is held in afluid tight fit in the check valve assembly by a resilient sealing ring25 which is adapted to permit easy detachment of the syringe tip fromthe check valve assembly.

In operation, when the motor shaft is rotated by the motor, the Scotchyoke reciprocates the plunger within the cylindrical body 11. When theplunger is forced inwardly, a relatively high pressure is created in thecylindrical body, and fluid in the check valve chamber 19 and the bodywill be forced therefrom through the valve 24a which is forced upon bythe high pressure created by the piston 13. The duckbill valve 24b isheld closed by the high pressure, and thus fluid can only flow to theoutlet through valve 4a.

On the downstroke of the piston 13, a partial vacuum is created in thecylindrical body 11 and fluid is drawn through the check valve 24b intothe chamber 20 and into the cylindrical body 11 of the piston syringe10. The vacuum created causes the duckbill valve 24a to remain closedand prevents fluid from passing to the outlet 22.

If a dilferent capacity pump were required, or if the syringe becameworn, the syringe 10 can be readily detached from the assembly by merelyremoving the check valve member from the snap clips 26 which hold it inposition, and detaching it from the syringe 10. The syringe can beremoved by pulling it from the snap clips 15 and 17 and sliding it fromthe C-clamp 6 of the Scotch yoke assembly.

As can be seen by reference to FIGURE 1, this can all be readilyaccomplished without any difliculty. A syringe of the same size, or of adifferent size can be inserted in its place in a short time and withoutany substantial effort.

In FIGURE 2, a multiple syringe pump assembly is shown. It comprisesfour surgical syringes 30, which are all similar to that described abovein connection with the previous embodiment. Each of these syringescommunicates with a check valve assembly 32, also similar to thatdescribed above. Syringes are held in place by snap clips 35 and 37which engage the body of the syringe, and the end flange of eachsyringe, respectively. Each of the syringes is provided with acompression spring 40 which normally holds the plunger in a withdrawnposition. The syringes are mounted in a starlike configuration centeringabout the drive means. Four syringes are shown, however, and more thanfour syringes could be provided, if desired. The plungers of thesyringes are all arranged to point inwardly and forced by the syringetoward a cam 45, centrally located with regard to the plungers. This camis mounted on a motor shaft 47.

When the motor shaft is rotated, the cam rotates, sequentiallydepressing the plunger of the adjacent syringe as it rotates. Thecompression springs return the plungers to their withdrawn position assoon as the apex of the cam passes each plunger and permits suchmovement. As the plungers reciprocate due to the motion of the cam,fluid is pumped through the check valve assemblies in a manner similarto that described above.

It is to be noted that in this embodiment, the syringes can be of allthe same size or of different sizes, and each of the syringes can bereadily detached in a place independently of the others.

In FIGURE 3, another embodiment of the syringe pump in accordance withthis invention is shown. It comprises a nylon base 50, housing a motor(not shown). The motor is operatively connected to an eccentric drivemechanism by a drive wheel 52, via a motor shaft 53. An eccentric drivepin 54 is located on the drive wheel 52. The drive pin is operativelyconnected to a pivoted yoke mechanism 56. The yoke comprises a pivotedbar 58 having a slotted portion at one end 59, for reception of the pin54, and a lever portion 60, at the other end thereof. The drive pin 54is located within the slotted portion 59 for pivotally moving the leverportion 60 upon rotation of the drive wheel 52. The lever portion 60engages a plunger drive mechanism 61 for reciprocally moving a syringeplunger 64 within a syringe body 65. The plunger drive mechanism 61comprises a carriage 62 having a slotted portion 63 which engages theend 66 of a plunger 64. The carriage is movable in the same direction asis the plunger in a slot (not shown) via a key 67. A set screw 68 islocated adjacent to the lever portion 60 of the yoke drive 56 to limitthe extent of the reciprocal motion of the plunger 64, upon pivotalmotion of the yoke drive 56.

The syringe, which consists of a barrel portion 65, a plunger portion64, a flanged end 70, and an aperture tip 72, is mounted on the housingwith the plunger end i 7 66 within the slotted portion of the plungerdrive mechanism and the flanged portion 70 within a pair of pincer snapclips 75. The pincer snap clips are composed of a rigid section 75a anda resilient arm member 75b. The resilient arm is made of spring steeland tightly holds the flange of the syringe in position as the plungerof the syringe is reciprocated within the body portion 65. The syringeis easily demountable from the assembly by merely sliding it from thesnap clips 75, and removing the plunger end 66 from the plunger drivemechanism 61.

The apertured tip of the plunger is inserted within a check valveassembly 76. The check valve assembly is provided with two duckbillvalves 77, disposed within a check valve chamber 78 at the inlet andoutlet of the chamber. The inlet and the outlet of the chamber areconnected to a fluid line for flow through the assembly. The duckbillvalves are arranged such that fluid can proceed only through theassembly in one direction.

A tapered passage 79 is formed in the check valve chamber between theinlet and outlet. This passage is formed to the same taper as theapertured tip of the syringe and seals thereagainst to prevent leakageof fluid from the assembly. The check valve chamber can be easilyremoved from the syringe by merely twisting it, thus breaking the sealand thereby loosening it, such that it can be easily removed from theassembly.

In operation, upon rotation of the motor shaft 53, the drive wheel 52 isrotated, thus causing eccentric motion of the pin 54. This pin moves thelever 60 of the yoke drive 56, thus causing reciprocal motion of theplunger within the body of the syringe. Fluid is pumped through thefluid line in measured amounts.

The plunger can be readily removed from the assembly by merelywithdrawing it from the snap clips and the yoke and plunger drivemechanism in the manner described. The apertured tip can then be removedfrom the check valve chamber by merely twisting it to break the seal.

Thus, the instant invention has provided a simple and inexpensivelyconstructed syringe pump adapted to serve many functions with a minimumof expense and with a maximum of versatility.

Having regard to the foregoing disclosure, the following is claimed asthe inventive and patentable embodiments thereof:

1. A syringe pump adapted to interchangeably employ one or more of aseries of similar syringes of the same or different sizes comprising, incombination, a syringe having a body portion including at least abarrel, a fluidpumping plunger reciprocably movable in the barrel andhaving retaining means thereon, and an aperture in the body portioncommunicating with the barrel for entry of fluid to and exit of fluidfrom the barrel upon fluid-pumping reciprocation of the plunger; drivemeans including a motor operatively associated with the plunger forreciprocably moving the plunger within the barrel to draw fluid into thebarrel and pump it out; coupling means holding in operative engagementin an easily detachable manner both the drive means and the retainingmeans on the fluid-pumping plunger, said coupling means being adapted toaccommodate the retaining means on the plungers of any of a series ofsyringes of the same or different sizes; mounting means engaging thebody portion in an easily detachable manner, and being adapted to holdthe body portion of any of such series of syringes in a fixed positionrelative to the drive means, such that upon operation of the drive meansthe plunger is reciprocated in the barrel; and a check valve assembly influid connection with the aperture and barrel, such that fluid can bedrawn into and pumped from the barrel of the syringe by the plunger,whereby upon operation of the drive means, the plunger is reciprocatedand fluid is pumped through the check valve assembly in only onedirection.

2. A syringe pump in accordance with claim 1 in which the body portionof the syringe has a flange, and

in which the mounting means engages the flange on the body portion.

3. A syringe pump in accordance with claim 1 in the drive means includesa cam.

4. A syringe pump in accordance with claim 1 in which the retainingmeans comprises a flange on the end ofthe plunger.

5. A syringe pump in accordance with claim 1, in which the couplingmeans is a yoke.

6. A syringe pump in accordance with claim 1 in which the coupling meansincludes a spring.

7. A syringe pump in accordance with claim 1 in which the mounting meanscomprises snap clips.

8. A syringe pump in accordance with claim 7, in which the snap clipsinclude pincers.

9. A syringe pump in accordance with claim 1 in which the mounting meanscomprises clamps.

10. A syringe pump in accordance with claim 1 in which the aperture inthe syringe is in a tapered tip on the end of the syringe barrel and inWhich the check valve assembly is mounted on the tip.

11. A syringe pump in accordance with claim 1 including means forcontrolling the length of the stroke of the fluid-pumping plunger in thebarrel.

12. A syringe pump adapted to interchangeably employ one or more of aseries of similar syringes, of the same or different sizes comprising,in combination, a base; drive means associated with the base, includinga motor and an eccentric drive mechanism connected to the motor; atleast one syringe detachably mounted on the base, said syringecomprising a cylindrical body having an aper;

tured tip at one end thereof and a laterally extending flange at theopposite end thereof; a fluid pumping plunger reciprocably movable inthe cylindrical body, said pumping plunger having a retaining means onthe end thereof, and being adapted to upon reciprocation thereof drawfluid into the cylindrical body through the aperture in the tip;coupling means holding in operative engagement in an easily detachablemanner, the drive means and the retaining means on the fluid pumpingplunger, said coupling means being adapted to accommodate the retainingmeans on the plungers of a series ofsyringe's of the same or differentsizes; mounting means on the base engaging at least the flange on thecylindrical body of the syringe in an easily detachable manner and beingadapted,

to hold flanges of such series of syringes in a fixed position on thebase, such that upon operation of the drive means the plunger isreciprocated within the cylindrical body; a check valve assembly mountedon the'tip of the syringe, said check valve assembly comprising achamber having an inlet and an outlet; and check valves closing off theinlet and the outlet and permitting fluid flow through the assembly fromthe inlet tothe outlet upon reciprocation of the plunger, such thatfluid is drawn into and pumped from the cylindrical barrel of thesyringe,

whereby upon operation of the drive means, the plunger is reciprocatedand fluid is pumped through the check valve assembly only in onedirection.

References Cited UNITED STATES PATENTS which

